In the wake of the Battle of the Little Bighorn, Col. Nelson A. Miles founded the post in August 1876 as a base for cavalry patrols, to prevent the Cheyenne and Sioux involved in the battle from escaping to Canada. It was originally called the Tongue River Cantonment for the first year or so. When relocated a mile away it was renamed Fort Keogh in honor of Captain Myles Keogh, who died at the Battle of the Little Bighorn. In 1877 the fort became the headquarters for the newly created military district, the District of the Yellowstone (a subunit of the Department of Dakota), commanded by Miles. He was promoted to brigadier general in September the same year.